@article{IVM_1975_4_a2,
     author = {A. K. Guts},
     title = {Mappings of families of sets in {a~Loba\v{c}evski\u{i}} space},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {24--32},
     year = {1975},
     number = {4},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_1975_4_a2/}
}